This invention relates to multi-speed transmissions and, more particularly, to five speed transmissions having two simple planetary gear sets.
Automotive vehicles have a powertrain that generally includes an engine, a starting device, and a power transmission. The transmission is, in most vehicles, a multi-speed unit that utilizes either a planetary gear arrangement or a countershaft gearing mechanism. More recently, some manufacturers have produced variable type units. However, the most popular of these transmissions appears to be the automatic shifting, multi-speed planetary gearing mechanisms.
The planetary type transmissions have evolved from two speed units to four and five speed units in passenger vehicles. Some heavy trucks have employed six or more speed ratios. However, these truck units are not adaptable to passenger vehicles. The four and five speed transmissions permit better use of the engine operating range by allowing the performance to remain within the maximum torque range during vehicle acceleration and at the best fuel consumption rate during cruising speeds.
It is an object of the present invention to provide an improved multi-speed power transmission.
In one aspect of the present invention, two simple planetary gear sets are controlled to provide five forward speed ratios and one reverse ratio. In another aspect of the present invention, the planetary gear sets are controlled by six torque transmitting mechanisms.
In yet another aspect of the present invention, one of the planetary gear members is continually connected with a stationary member of the transmission. In still another aspect of the present invention, the transmission has a low mechanical content including the gearing and torque transmitting mechanisms. In a further aspect of the present invention, the six torque transmitting mechanisms include five rotating torque transmitting mechanisms (clutches) and one stationary torque transmitting mechanism (brake). In a yet further aspect of the present invention, two of the rotating torque transmitting mechanisms provide input connections, two of the rotating torque transmitting mechanisms provide interconnections, and one of the rotating torque transmitting mechanisms provides an output connection for the planetary gear sets.